1. Field of the Invention
The present invention relates to a digital television, and more particularly to, an apparatus for converting a format for a digital television.
2. Description of the Related Art
According to the introduction of digital TVs and various display apparatuses, more various kinds of images become possible to be input and output in comparison with an existing analogue TVs. In order to convert input images of various sizes into output images of different sizes, a format conversion apparatus is essential and in order to obtain a high resolution output, proper filtering should be performed in vertical and horizontal directions, according to a ratio of input and output images.
Now, related arts will be described with reference to appended drawings.
FIG. 1 is a block diagram showing an apparatus for converting a format for digital TVs, according to the background art. The apparatus includes a first line memory 1 and a second line memory 2 for temporarily storing input image signals, a vertical format converter 3 for converting vertical components included in the image signals output from the first line memory 1 and the second line memory 2 in a predetermined format, a horizontal filter 4 for filtering horizontal components included in the image signals of which format is vertically converted by the vertical format converter 3 by a predetermined bandwidth, a horizontal format converter 5 for outputting the image signals filtered by the horizontal filter 4 after converting into a predetermined format, and a memory 6 for storing input images for format conversion and outputs to the first and second line memories 1, 2 and displaying the image of which format is converted in the horizontal format converter 5.
In FIG. 1, the input image signals are stored in the memory 6 and then outputted to the first and second line memories 1, 2 for format conversion. The first and second line memories 1, 2 store the image signals output from the memory 6 temporarily and output to the vertical format converter 3.
The vertical format conversion element 3 converts the vertical components included in the image signals which are output from the first and second line memories 1, 2 into an output image size and outputs to the horizontal filter 4.
The horizontal filter 4 filters the horizontal components included in the image signals which are converted and output by the vertical format conversion element 3 and outputs to the horizontal format conversion element 5. That is, the horizontal filter 4 limits the bandwidth of the input image for preventing aliasing possibly generated when reducing the input image in the horizontal direction. The image signals, which are filtered in the horizontal direction, are stored in the memory 6 after the horizontal format conversion by the horizontal format conversion element 5 in accordance with the output size.
At this time, if the line memories as shown in FIG. 1 are utilized, waste of the memory is increased. That is, an amount of required hardware is increased since the size of the respective line memories is determined by the size of input images, which are not converted in format. In particular, when processing images of high definition television (HDTV) receivers, line memories corresponding to the high-resolution images are required so that an amount of a total hardware is extremely increased.
If buffers are adopted to avoid this disadvantage, even though the size of the hardware may be reduced but a relatively larger memory bandwidth is required. That is, in case that buffers are adopted, vertical filters of a plurality of taps should be used for obtaining a high resolution and the memory bandwidth is greatly increased. Therefore, the vertical filtering is imitatively used in an expensive system. Finally, low price systems, which can not adopt the vertical filtering, can not obtain an image quality as required.
An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
Another object of the present invention is to provide an apparatus for converting a format of digital TVs in which input images are divided into a plurality of blocks and the respective blocks are converted in vertical and horizontal directions.
To achieve at least these and other advantages in whole or in parts there is provided an apparatus for converting a format for a digital TV, comprising, a block division and control signal generating part for dividing an input image into a plurality of blocks according to an input image size data and an output image size data, and generating a control signal for performing format conversion per the divided blocks; a format conversion coefficient generating part for generating a format conversion coefficient for converting formats per block according to a control signal output from the block division and control signal generating part; a synchronizing signal generating part for generating vertical and horizontal synchronizing signals per block according to a control signal output from the block division and control signal generating part; and a format conversion part for performing format conversion per block according to the format conversion coefficient generated from the format conversion coefficient generating part and the vertical and horizontal synchronizing signals generated from the synchronizing signal generating part.
The blocks divided in the block division and control signal generating part is overlapped with other neighboring blocks in part.
The apparatus for converting a format for a digital TV further comprises a read/write address generating part for generating a read address and a write address according to a control signal output from the block division and control signal generating part, and a memory for performing read/write of an input image according to the read address and the write address, wherein blocks read in the format conversion part according to the read address is read by overlapping with neighboring blocks in part, and blocks which are written after the format conversion are written without overlapping with neighboring blocks according to the write address.
The block division and control signal generating part determines a block size when dividing an input image into a plurality of blocks according to a memory bandwidth.
The block division and control signal generating part determines a horizontal direction size of the respective blocks to be slightly smaller than a pixel number able to be brought by a signal memory read operation.
The format conversion coefficient generating part generates format conversion coefficients in such a manner that a format conversion coefficient at a starting point of the respective blocks which are divided from an input image into a plurality of blocks under the control of the block division and control signal generating part is in conformity with a format conversion coefficient at a point when the input image is processed by a single block.
The synchronizing signal generating part generates vertical and horizontal synchronizing signals equal or different for the respective blocks, which are divided under the control of the block division, and control signal generating part.
The format conversion part comprises a memory buffer part including a plurality of buffers for temporarily storing images input per block unit, a vertical format conversion part for converting an image signal output from the memory buffer part in the vertical direction according to a format conversion coefficient generated from the format conversion coefficient generating part and a vertical synchronizing signal generated from the synchronizing signal generating part, and a horizontal format conversion part for converting an image signal output from the vertical format conversion part in the horizontal direction according to a format conversion coefficient generated from the format conversion coefficient generating part and a horizontal synchronizing signal generated from the synchronizing signal generating part.
The block division and control signal generating part determines a block size according to a size of the memory buffer when dividing the input image into a plurality of blocks.
The plurality of buffers in the memory buffer part is disposed in parallel, and a number of the buffers is determined by a number of taps of the vertical filter at a rear end.
The block division and control signal generating part divides a horizontal direction size of a block to be smaller than a pixel number stored in a single buffer when dividing the input image into a plurality of blocks.
The apparatus for converting a format for a digital TV includes a block division and control signal generating part for dividing an input image into a plurality of blocks according to an input image size data, an output image size data and an input and output size data of each block, and generating a control signal for performing format conversion per the divided blocks, a format conversion coefficient generating part for generating a format conversion coefficient for converting formats per block according to a control signal output from the block division and control signal generating part, a synchronizing signal generating part for generating vertical and horizontal synchronizing signals per block according to a control signal output from the block division and control signal generating part, and a format conversion part for performing format conversion per block according to the format conversion coefficient generated from the format conversion coefficient generating part and the vertical and horizontal synchronizing signals generated from the synchronizing signal generating part.
The apparatus for converting a format of a digital TV further includes a read/write address generating part for generating a read address and a write address according to a control signal output from the block division and control signal generating part, and a memory for performing read/write of an input image according to the read address and the write address, wherein blocks read in the format conversion part according to the read address is read by overlapping with neighboring blocks in part, and blocks which are written after the format conversion are written without overlapping with neighboring blocks according to the write address.
The blocks divided in the block division and control signal generating part are overlapped with other neighboring blocks in part.
The format conversion coefficient generating part generates format conversion coefficients differently for the respective blocks which are divided under the block division and control signal generating part for performing the format conversion of blocks with different input and output sizes.
The synchronizing signal generating part generates vertical and horizontal synchronizing signals differently for the respective blocks which are divided under the control of the block division and control signal generating part for performing the format conversion of blocks with different input and output sizes.
The format conversion part includes a memory buffer part including a plurality of buffers for temporarily storing images input per block unit, a vertical format conversion part for converting an image signal output from the memory buffer part in the vertical direction according to a format conversion coefficient generated from the format conversion coefficient generating part and a vertical synchronizing signal generated from the synchronizing signal generating part, and a horizontal format conversion part for converting an image signal output from the vertical format conversion part in the horizontal direction according to a format conversion coefficient generated from the format conversion coefficient generating part and a horizontal synchronizing signal generated from the synchronizing signal generating part.
A vertical filter and a horizontal filter are provided respectively at a front end part of the vertical format conversion part and a front end part of the horizontal conversion part for limiting bandwidth of an input image.
According to the present invention, input images are divided into a plurality of blocks and the blocks are converted vertically and horizontally in the format by using the buffers like the line memories, so that the buffer memory and the bandwidth required for the format conversion are simultaneously reduced greatly, thereby preventing degradation of resolution generated when reducing a size of an image and realizing a high resolution with simple hardware.